A process of manufacturing a semiconductor device in which a stacking structure of an integrated circuit is formed on the surface of a substrate to be processed such as a semiconductor wafer (hereinafter, referred to as a wafer), includes a liquid process of processing the wafer surface by using a liquid to remove minute dusts or a native oxide layer on the wafer surface with a washing fluid such as a chemical solution.
For example, a single-type spin washing apparatus washing the wafer removes dusts or a native oxide on the wafer surface by rotating the wafer while supplying alkaline or acid chemical solutions to the surface of the wafer by using a nozzle. In this case, after remaining chemical solutions are removed from the wafer surface by rinse washing using, for example, deionized water, and thereafter, the wafer surface is dried by brushing dry of brushing away the remaining solutions by rotating the wafer.
However, with a high integration of the semiconductor device, a problem in so-called a pattern collapse has been growing seriously in a processing of removing the solutions. The pattern collapse is a phenomenon in which at the time of drying the remaining solutions on the wafer surface, the remaining solutions are unevenly dried at the left and right sides of a convex of concave and convex portions forming a pattern, the balance of the surface tension horizontally pulling the convex is lost, and as a result, the convex falls down in a direction in which more solutions remain.
As a technique of removing the solutions remaining on the wafer surface while suppressing the pattern collapse, a drying method using a supercritical liquid-state fluid (a supercritical fluid) is widely known. The supercritical fluid has lower viscosity than that of a liquid, and it also has a higher ability to dissolve the liquid. In addition, there is no interface between a liquid and a gas at an equilibrium state of the supercritical fluid. Therefore, the liquid attached to the wafer is replaced with the supercritical fluid, and thereafter, when the supercritical fluid is changed to a gaseous state, the liquid may be dried without being influenced by the surface tension.
Herein, Japanese Patent Application Laid-Open No. 2008-72118 in paragraphs [0025] to [0029] along with FIG. 1 discloses a technology in which a substrate washed by a washing unit is transferred into a drying apparatus by using a substrate transferring robot and the substrate is brought into contact with the supercritical fluid to remove a washing fluid attached to the surface of the substrate. In the technology disclosed in Paragraphs [0025] to [0029] and FIG. 1 of Japanese Patent Application Laid-Open No. 2008-72118, a substrate to be processed is carried into a transfer chamber to be transferred to the transferring robot. The substrate is then transferred to a drying processing chamber and the corresponding substrate is dried by using the supercritical fluid. As a result, a liquid on the surface of the substrate is dried before the processing starts, and the pattern collapse may occur.